The synthesis of Vitamin E, that is, alpha-tocopherol (5,7,8-trimethyltocol) in the past has been accomplished primarily by reacting trimethylhydroquinone (TMHQ) with isophytol (3,7,11,15-tetramethylhexadec-1-en-3-ol) or phytol (3,7,11,15-tetramethylhexadec-2-en-1-ol) in a condensation reaction. The reaction is well known and has been practiced for many years.
The various routes to phytol and isophytol have been reviewed by Stalla-Bourdillon, Ind. Chim. Belg., 35, 13 (1970); and also in "The Vitamins," Vol. 5, pages 168-223, Academic Press, New York, 1967. With few exceptions, these routes utilize a C.sub.10 intermediate (natural or synthetic) and proceed to the C.sub.20 phytol or isophytol by sequential addition of various carbon units (C.sub.4 or less). The steps are numerous, and the snytheses are costly.
In copending application Ser. No. 353,215, filed Apr. 23, 1973, now U.S. Pat. No. 3,949,006, on "Synthesis of Vitamin A Intermediates and Conversion Thereof to Vitamin A," by William Oroshnik, a novel process is disclosed which comprises forming an ethynyl-terminated alkoxy-substituted beta-ionol intermediate from beta-ionone and then coupling such intermediate with a compound like "isoprene chloroacetate" (1-acetoxy-4-chloro-3-methylbut-2-ene) to produce a C.sub.20 skeleton. The latter by semi-hydrogenation, hydrolysis and treatment with a strong base produced Vitamin A. The invention of copending application Ser. No. 353,215 resides in part in the discovery that successful coupling of the intermediate and isoprene chloroacetate permitted elimination of at least one additional step in the Vitamin A synthesis. The present invention resides in part in the discovery that "isoprene chloroacetate" is also a useful reactant in the synthesis of Vitamin E.